Bogus “Reverse DNS does not match SMTP Banner” using MX Toolbox on a WHM server
When testing Email Health using MX Toolbox, you might get 3 false positives: smtp server.example.com Reverse DNS does not match SMTP Banner More Info smtp
greylisting
How to whitelist a domain in Virtualmin that is being delayed by Greylisting all the time
Background Greylisting is a common technique to keep once-off spammers away from a mail server. By using timing and a triplet system based on sender
Why does it take exactly two minutes for my email to get delivered to Gmail’s server?
Quick answer: Greylisting. Long answer: Read this: https://forum.netcup.de/anwendung/sonstige-anwendungen/p82197-warum-ist-sendmail-so-langsam-php-mail/ or summarised: Greylisting: Greylisting refers to a form of spam control for emails, in which the first